Effect of the oxide-desorption temperature on the substrate–epilayer interface charge in organometallic vapor-phase epitaxy of GaAs

Abstract

We found that the use of relatively low temperatures during oxide desorption in organometallic vapor-phase epitaxy of GaAs reduced the epilayer–substrate interface charge. No differences in Hall mobility were found between the samples grown with 550 and 650 °C desorption. O, C, Si, and S were the dominant impurities at the interface. Si and S, which are shallow donors, induce the interface-charge accumulation. Low-temperature desorption leaves oxygen at the surface, suppressing the activation of shallow dopants. A high level (≳1×1012/cm2) of Cl was detected on every GaAs substrate we measured, but its effect on epitaxy is not clear.